Catecholamine dysfunction in attention-deficit/hyperactivity disorder: an update

Adherence-Promoting Design Features in Pediatric Neurostimulators for ADHD Patients

The emergence of remote health monitoring and increased at-home care emphasizes the importance of patient adherence outside the clinical setting. This is particularly pertinent in the treatment of Attention Deficit Hyperactivity Disorder (ADHD) in pediatric patients, as the population inherently has difficulty remembering and initiating treatment tasks. Neurostimulation is an emerging treatment modality for pediatric ADHD and requires strict adherence to a treatment regimen to be followed in an at-home setting. Thus, to achieve the desired therapeutic effect, careful attention must be paid to design features that can passively promote and effectively monitor therapeutic adherence. This work describes instrumentation designed to support a clinical trial protocol that tests whether choice of color, or color itself, can statistically significantly increase adherence rates in pediatric ADHD patients in an extraclinical environment. This is made possible through the development and application of an internet-of-things approach in a remote adherence monitoring technology that can be implemented in forthcoming neurostimulation devices for pediatric patient use. This instrumentation requires minimal input from the user, is durable and resistant to physical damage, and provides accurate adherence data to parents and physicians, increasing assurance that neurostimulation devices are effective for at-home care.

Serum ciliary neurotrophic factor levels in children with attention deficit hyperactivity disorder

Purpose/aim of the study: The study aimed to highlight the possible role of ciliary neurotrophic factor (CNTF) in the pathophysiology of attention deficit hyperactivity disorder (ADHD) and determine whether CNTF can be used as a biomarker for ADHD.Materials and methods: Patients with a diagnosis of ADHD and neurotypical subjects aged 6-12 years were recruited prospectively. The study applied Conners' Teacher Rating Scale (CTRS) to determine the patients' ADHD predominance and severity. Serum CNTF levels were measured with an enzyme-linked immunosorbent assay (ELISA) kit.Results: A total of 43 ADHD patients and 33 healthy controls were included in the study. A significant difference was found between the serum CNTF levels of the ADHD patients (22.17 pg/ml) and the controls (22.80 pg/ml). Correlations between the CNTF levels and CTRS scores were not significant.Conclusions: The study identified an alteration of serum CNTF levels in ADHD patients and thus asserted a link between CNTF and ADHD pathophysiology; children with ADHD had significantly lower serum CNTF levels compared to the neurotypical controls. Further research is needed to understand the mechanisms of CNTF.

Adult ADHD: it is old and new at the same time - what is it?

Even though the number of studies aiming to improve comprehension of ADHD pathology has increased in recent years, there still is an urgent need for more effective studies, particularly in understanding adult ADHD, both at preclinical and clinical levels, due to the increasing evidence that adult ADHD is highly distinct and a different entity from childhood ADHD. This review paper outlines the symptoms, diagnostics, and neurobiological mechanisms of ADHD, with emphasis on how adult ADHD could be different from childhood-onset. Data show a difference in the environmental, genetic, epigenetic, and brain structural changes, when combined, could greatly impact the behavioral presentations and the severity of ADHD in adults. Furthermore, a crucial aspect in the quest to fully understand this disorder could be through longitudinal analysis. In this way, we will determine if and how the pathology and pharmacology of ADHD change with age. This goal could revolutionize our understanding of the disorder and address the weaknesses in the current clinical classification systems, improving the characterization and validity of ADHD diagnosis, specifically those in adults.

[Is Physical Activity a Treatment Option for ADHD?]

Is Physical Activity a Treatment Option for ADHD? Abstract: Physical activity as an option for the prevention and treatment of psychiatric disorders is increasingly becoming the focus of research. In particular, because of improvements in cognitive functioning, attentional performance, impulsivity, and hyperactivity, physical exercise could be a promising treatment option for attention deficit hyperactivity disorder (ADHD). In this narrative review, we present and evaluate the current state of research on exercise effects in children and adolescents as well as in adults with ADHD. While studies of the short-term effects of a single bout of physical activity indicate robust effects on attention and inhibitory control, results on the impact on further symptoms of ADHD as well as in adults are mixed. Randomized controlled trials of longer-term physical activity are scarce and show high heterogeneity. Nevertheless, they are encouraging for further research in this area.

BH4 as a Therapeutic Target for ADHD: Relevance to Neurotransmitters and Stress-Driven Symptoms

Tetrahydrobiopterin (BH4) is a critical cofactor in a variety of metabolic pathways that have been linked to ADHD. There have been no previous studies utilizing BH4 as a supplement for ADHD. BH4 has been approved as a treatment for phenylketonuria (PKU). Individuals with PKU and ADHD appear to have low DA levels in common, suggesting that the hypodopaminergic state seen in both illnesses could be a relationship between the two. Clinical research involving supplementation of BH4 has shown low occurrence of adverse. In experiments, BH4 has also been found to have good blood-brain barrier permeability. BH4 also has the ability in scavenging ROS activity, which is an implication of stress and is seen in ADHD. BH4's significance in ADHD is reviewed in this paper because of its involvement in numerous neurodevelopmental metabolic pathways, and we anticipate that exogenous BH4 can be used to treat ADHD.

The effects of methylphenidate and atomoxetine on Drosophila brain at single-cell resolution and potential drug repurposing for ADHD treatment

The stimulant methylphenidate (MPH) and the non-stimulant atomoxetine (ATX) are frequently used for the treatment of attention-deficit/hyperactivity disorder (ADHD); however, the function of these drugs in different types of brain cells and their effects on related genes remain largely unknown. To address these questions, we built a pipeline for the simultaneous examination of the activity behavior and transcriptional responses of Drosophila melanogaster at single-cell resolution following drug treatment. We selected the Drosophila with significantly increased locomotor activities (hyperactivity-like behavior) following the administration of each drug in comparison with the control (same food as the drug-treated groups with 5% sucrose, yeast, and blue food dye solution) using EasyFlyTracker. Subsequently, single cell RNA sequencing (scRNASEQ) was used to capture the transcriptome of 82,917 cells, unsupervised clustering analysis of which yielded 28 primary cell clusters representing the major cell types in adult Drosophila brain. Indeed, both neuronal and glial cells responded to MPH and ATX. Further analysis of differentially expressed genes (DEGs) revealed distinct transcriptional changes associated with these two drugs, such as two well-studied dopamine receptor genes (Dop2R and DopEcR) were responsive to MPH but not to ATX at their optimal doses, in addition to genes involved in dopamine metabolism pathways such as Syt1, Sytalpha, Syt7, and Ih in different cell types. More importantly, MPH also suppressed the expression of genes encoding other neurotransmitter receptors and synaptic signaling molecules in many cell types, especially those for Glu and GABA, while the responsive effects of ATX were much weaker. In addition to monoaminergic neuronal transmitters, other neurotransmitters have also shown a similar pattern with respect to a stronger effect associated with MPH than with ATX. Moreover, we identified four distinct glial cell subtypes responsive to the two drugs and detected a greater number of differentially expressed genes associated with ensheathing and astrocyte-like glia. Furthermore, our study provides a rich resource of candidate target genes, supported by drug set enrichment analysis (P = 2.10E-4; hypergeometric test), for the further exploration of drug repurposing. The whole list of candidates can be found at ADHDrug ( http://adhdrug.cibr.ac.cn/ ). In conclusion, we propose a fast and cost-efficient pipeline to explore the underlying molecular mechanisms of ADHD drug treatment in Drosophila brain at single-cell resolution, which may further facilitate drug repurposing applications.

Noradrenaline tracks emotional modulation of attention in human amygdala

The noradrenaline (NA) system is one of the brain's major neuromodulatory systems; it originates in a small midbrain nucleus, the locus coeruleus (LC), and projects widely throughout the brain.1,2 The LC-NA system is believed to regulate arousal and attention3,4 and is a pharmacological target in multiple clinical conditions.5,6,7 Yet our understanding of its role in health and disease has been impeded by a lack of direct recordings in humans. Here, we address this problem by showing that electrochemical estimates of sub-second NA dynamics can be obtained using clinical depth electrodes implanted for epilepsy monitoring. We made these recordings in the amygdala, an evolutionarily ancient structure that supports emotional processing8,9 and receives dense LC-NA projections,10 while patients (n = 3) performed a visual affective oddball task. The task was designed to induce different cognitive states, with the oddball stimuli involving emotionally evocative images,11 which varied in terms of arousal (low versus high) and valence (negative versus positive). Consistent with theory, the NA estimates tracked the emotional modulation of attention, with a stronger oddball response in a high-arousal state. Parallel estimates of pupil dilation, a common behavioral proxy for LC-NA activity,12 supported a hypothesis that pupil-NA coupling changes with cognitive state,13,14 with the pupil and NA estimates being positively correlated for oddball stimuli in a high-arousal but not a low-arousal state. Our study provides proof of concept that neuromodulator monitoring is now possible using depth electrodes in standard clinical use.

The influence of methylphenidate on auditory brainstem response patients with attention deficit hyperactivity disorder; an exploratory study

Background

Attention-deficit hyperactivity disorder (ADHD), characterized by periods of inattention, overactivity, and impulsiveness, is the most prevalent neurodevelopmental disorder among children. Auditory Brainstem Response (ABR) is a technique in which clickshaped sounds elicit potentials that are recorded from electrodes placed on a patient's skull. Extant research indicates that ABR is frequently affected in neurodevelopmental disorders such as ADHD. Methylphenidate (MPH), a psychostimulant, is often prescribed to children with ADHD as a first-line pharmacological treatment. The aim of this study was to explore the effects of Methylphenidate treatment on previously observed amplitude alterations in the ABR of patients with ADHD.

Methods

We recruited 32 drug-naïve children and adolescents (19 males and 13 females; mean age 11 years) diagnosed with ADHD and 35 health controls (15 males and 20 females; mean age 12 years). The ADHD group was treated with Methylphenidate, and ABR was recorded before treatment and at a steady state of medical treatment.

Results

Medicated ADHD patients exhibited increased activity in the right side ABR in Wave VI.

Conclusions

A significant increase in activity was found in a part of the ABR thought to correspond to the thalamic area in medicated ADHD patients compared to the same area of non-medicated ADHD patients. The results add to the growing body of research suggesting that specific ABR peaks correlate to certain psychiatric symptoms.

Alpha/beta-gamma decoupling in methylphenidate medicated ADHD patients

There is much interest to understand how different neural rhythms function, interact and are regulated. Here, we focus on WM delay gamma to investigate its coupling with alpha/beta rhythms and its neuromodulation by methylphenidate. We address this through the use of human EEG conducted in healthy and ADHD subjects which revealed ADHD-specific electrophysiological deficits and MPH-induced normalization of gamma amplitude and its coupling with alpha/beta rhythms. Decreased alpha/beta-gamma coupling is known to facilitate memory representations via disinhibition of gamma ensembles coding the maintained stimuli. Here, we present EEG evidence which suggests that these dynamics are sensitive to catecholaminergic neuromodulation. MPH decreased alpha/beta-gamma coupling and this was related to the increase in delay-relevant gamma activity evoked by the same drug. These results add further to the neuromodulatory findings that reflect an electrophysiological dimension to the well-known link between WM delay and catecholaminergic transmission.

The mesocortical dopaminergic system cannot explain hyperactivity in an animal model of attention deficit hyperactivity disorder (ADHD)- Spontaneously hypertensive rats (SHR)

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is one of the most prevalent neuropsychiatric disorders with morphological brain abnormalities. There is a growing body of evidence that abnormalities in the dopaminergic system may account for ADHD pathogenesis. However, it is not clear whether the dopaminergic system is hyper or hypoactive. To determine whether the DA neurons and/or axons deficiency might be the cause of the postulated dopaminergic hypofunction in spontaneously hypertensive rats (SHR, animal model of ADHD), this study examined the dopaminergic neurons and fibers in the brain tissues of SHRs and Wistar Kyoto rats (WKY, control animals). Here, we performed immunohistochemical tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) staining on brain sections collected on juveniles from SHR and WKY. Moreover, behavioral testing to examine the hyperactivity in the open field area was also elucidated.

RESULTS

The mesocortical dopaminergic system appears to be normal in juvenile SHR, as suggested by (i) no alteration in the area density of TH-immunoreactive (TH-ir) dopaminergic neurons in the ventral tegmental area (VTA), (ii) no alterations in the volume density of TH-ir fibers in layer I of the prelimbic (PrL) subregion of medial PFC (mPFC), (iii) no alteration in the percentage of TH-ir dopaminergic fibers in layer I of the PrL subregion of mPFC as revealed by TH and/or DBH immunoreactivity. Furthermore, the SHR showed increased locomotor activity than WKY in the open field test.

CONCLUSIONS

The demonstration of no alteration in mesocortical dopaminergic neurons and fiber in SHR raises some concern about the position of SHR as an animal model of the inattentive subtype of ADHD. However, these results strengthen this strain as an animal model of hyperactive/impulsive subtype ADHD for future studies that may elucidate the underlying mechanism mediating hyperactivity and test various treatment strategies.

l-Arginine/nitric oxide pathway and oxidative stress in adults with ADHD: Effects of methylphenidate treatment

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is a mental disorder that was once thought to occur only in children. Meanwhile, it is known that adults can also be affected. The first-line drug in children and adults to treat symptoms of inattention, impulsivity, lack of self-regulation, and hyperactivity is methylphenidate (MPH). Known adverse effects of MPH include cardiovascular problems, such as elevated blood pressure and heart rate. Therefore, biomarkers to monitor potential cardiovascular side effects of MPH are needed. The l-Arginine/Nitric oxide (Arg/NO) pathway is involved in noradrenaline and dopamine release as well as in normal cardiovascular functioning and is therefore a prime candidate for the search of biomarkers. The aim of the present study was to investigate the Arg/NO pathway as well as oxidative stress in adult ADHD patients in plasma and urine and the potential influence of MPH medication.

METHODS

In plasma and urine samples of 29 adults with ADHD (39.2 ± 10.9 years) and 32 healthy adults serving as controls (CO) (38.0 ± 11.6 years) the major NO metabolites nitrite and nitrate, Arg, the NO synthesis inhibitor asymmetric dimethylarginine (ADMA) and its major urinary metabolite dimethylamine (DMA) as well as malondialdehyde (MDA) were measured by gas chromatography-mass spectrometry.

RESULTS

Of the 29 patients with ADHD 14 were currently without MPH treatment (-MPH) and 15 were treated with MPH (+MPH). Plasma nitrate concentrations were significantly higher in patients not treated with MPH vs. CO (-MPH 60.3 μM [46.2-76.0] vs. CO 44.4 μM [35.0-52.7]; p = 0.002), while plasma nitrite tended to be higher in -MPH patients (2.77 μM [2.26-3.27]) vs. CO (2.13 μM [1.50-2.93]; p = 0.053). Additionally, plasma creatinine concentrations were significantly different, with -MPH showing significantly higher concentrations than the other two groups (-MPH 141 μM [128-159]; +MPH 96.2 μM [70.2-140]; Co 75.9 μM [62.0-94.7]; p < 0.001). Urinary creatinine excretion tended to be lowest in -MPH group vs. +MPH and CO (-MPH 11.4 ± 8.88 mM; +MPH 20.7 ± 9.82 mM; 16.6 ± 7.82 mM; p = 0.076). None of the other metabolites, including MDA, a marker of oxidative stress, showed a difference between the groups.

CONCLUSION

Adult patients with ADHD, who are not treated with MPH (-MPH), showed varied Arg/NO pathway, but Arg bioavailability seemed to be consistent over the groups. Our findings imply that urinary reabsorption may be increase and/or excretion of nitrite and nitrate may be decreased in ADHD, resulting in an increase in the plasma concentration of nitrite. MPH seems to partially reverse these effects by not yet known mechanisms, and does not affect oxidative stress.

Methylphenidate as a treatment option for substance use disorder: a transdiagnostic perspective

A transition in viewing mental disorders from conditions defined as a set of unique characteristics to one of the quantitative variations on a collection of dimensions allows overlap between disorders. The overlap can be utilized to extend to treatment approaches. Here, we consider the overlap between attention-deficit/hyperactivity disorder and substance use disorder to probe the suitability to use methylphenidate as a treatment for substance use disorder. Both disorders are characterized by maladaptive goal-directed behavior, impaired cognitive control, hyperactive phasic dopaminergic neurotransmission in the striatum, prefrontal hypoactivation, and reduced frontal cortex gray matter volume/density. In addition, methylphenidate has been shown to improve cognitive control and normalize associated brain activation in substance use disorder patients and clinical trials have found methylphenidate to improve clinical outcomes. Despite the theoretical basis and promising, but preliminary, outcomes, many questions remain unanswered. Most prominent is whether all patients who are addicted to different substances may equally profit from methylphenidate treatment.

The efficacy of physical exercise interventions on mental health, cognitive function, and ADHD symptoms in children and adolescents with ADHD: an umbrella review

Background

A considerable number of published reviews have addressed the effects of physical exercise on mental health, cognitive function, or attention-deficit hyperactivity (ADHD) symptoms as outcomes in children and adolescents with ADHD. Their findings have often conflicted, therefore, there is an urgent need to synthesise a hierarchy of the evidence and examine the credibility of previous meta-analyses. To establish the robustness of these findings, we conducted an additional meta-analysis on a number of individual studies that were not covered in previous reviews but were suitable for inclusion in our own study.

Methods

Three reviewers independently searched Web of Science, Psych INFO, Embase, Cochrane Library, PubMed, SPORTDiscus, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) for meta-analyses published between database inceptions to December 1, 2022. The individual studies were also screened from 1 January 2015 to 1 December 2022. We included meta-analyses and eligible individual studies that addressed the effects of exercise on at least one outcome of mental health, cognitive function, or ADHD symptoms in children and adolescents with ADHD. We excluded systematic reviews and articles that lacked sufficient data for a meaningful second analysis. The effect estimates (Hedges' g), 95% confidence interval (95% CI), 95% prediction interval (95% PI), small study effects, and excess significance bias were calculated. Finally, we categorised the meta-analyses based on the credibility of the evidence criteria and their quality using a Measurement Tool to Assess Systematic Reviews 2 checklist. This umbrella review was registered with PROSPERO, CRD42022361331.

Findings

Of 181 listed review articles and 60 individual papers, 10 reviews and 12 individual articles were included in the meta-analyses. This yielded 37 meta-analyses based on 106 study estimates. Evidence was highly suggestive for the effectiveness of exercise (class II) for improving inattention (G = 0.92, 95% CI: 0.44-1.39, 95%), inhibitory control (G = 0.82, 95% CI: 0.52-1.13), and cognitive flexibility (G = 0.52, 95% CI: 0.32-0.72). However, evidence for the effectiveness of exercise on emotional, social, and working memory outcomes was weak, and these results were not significant for hyperactivity and behavioural functioning.

Interpretation

Improvement of cognitive flexibility, inhibitory control, and inattention in children and adolescents with ADHD was highly suggested by exercise interventions. However, results were weak for other outcomes (emotional functioning, social functioning, and working memory). Further high-quality randomised controlled trials are, therefore, warranted to determine the effectiveness of exercise on weak outcomes.

Funding

None.

Pioglitazone enhances brain mitochondrial biogenesis and phase II detoxification capacity in neonatal rats with 6-OHDA-induced unilateral striatal lesions

The psychostimulant methylphenidate (MPH) is the first-line pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD), but has numerous adverse side effects. The PPARγ receptor agonist pioglitazone (PIO) is known to improve mitochondrial bioenergetics and antioxidant capacity, both of which may be deficient in ADHD, suggesting utility as an adjunct therapy. Here, we assessed the effects of PIO on ADHD-like symptoms, mitochondrial biogenesis and antioxidant pathways in multiple brain regions of neonate rats with unilateral striatal lesions induced by 6-hydroxydopamine (6-OHDA) as an experimental ADHD model. Unilateral striatal injection of 6-OHDA reduced ipsilateral dopaminergic innervation by 33% and increased locomotor activity. This locomotor hyperactivity was not altered by PIO treatment for 14 days. However, PIO increased the expression of proteins contributing to mitochondrial biogenesis in the striatum, hippocampus, cerebellum and prefrontal cortex of 6-OHDA-lesioned rats. In addition, PIO treatment enhanced the expression of the phase II transcription factor Nrf2 in the striatum, prefrontal cortex and cerebellum. In contrast, no change in the antioxidant enzyme catalase was observed in any of the brain regions analyzed. Thus, PIO may improve mitochondrial biogenesis and phase 2 detoxification in the ADHD brain. Further studies are required to determine if different dose regimens can exert more comprehensive therapeutic effects against ADHD neuropathology and behavior.

Inhibitory effect of atomoxetine on Nav1.2 voltage-gated sodium channel currents

BACKGROUND

Atomoxetine (ATX), a norepinephrine reuptake inhibitor (NRI), is used to attenuate the symptoms of Attention Deficit/Hyperactivity Disorder (AD/HD) by increasing neurotransmitter concentrations at the synaptic cleft. Although Nav1.2 voltage-gated sodium channels (VGSCs) are thought to play a role in monoamine transmitter release in the synaptic junction, it is unclear how atomoxetine affects Nav1.2 VGSCs.

METHODS

In this study, we investigated the effect of ATX on Nav1.2 VGSC-transfected HEK293 cells with the whole-patch clamp technique.

RESULTS

Nav1.2 VGSC current decreased by 51.15 ± 12.75% under treatment with 50 µM ATX in the resting state (holding membrane potential at - 80 mV). The IC₅₀ of ATX against Nav1.2 VGSC current was 45.57 µM. The activation/inactivation curve of Nav1.2 VGSC currents was shifted toward hyperpolarization by 50 µM ATX. In addition, the inhibitory effect of ATX increased with membrane depolarization (holding membrane potential at - 50 mV) and its IC₅₀ was 10.16 µM. Moreover, ATX showed the time-dependent interaction in the inactivation state.

CONCLUSION

These findings suggest that ATX interacts with Nav1.2 VGSCs producing the inhibition of current and the modification of kinetic properties in the state-dependent manner.

Atomoxetine Decreases Mitochondrial Biogenesis, Fission and Fusion In Human Neuron-like Cells But Does Not Alter Antioxidant Defences

Atomoxetine (ATX) is a presynaptic norepinephrine transporter (NET) inhibitor widely prescribed for attention-deficit/hyperactivity disorder (ADHD) due to its low abuse potential and absence of psychostimulant effects. While NET inhibition is implicated in the clinical response, several additional pharmacoactivities may contribute to clinical efficacy or unwanted side effects. We recently reported that ATX can dose-dependently alter mitochondrial function and cellular redox status. Here, we assessed potential alterations in mitochondrial biogenesis, mitochondrial dynamics and cellular antioxidant capacity following high- and low-dose ATX treatment of differentiated human neuroblastoma cells. Human SH-SY5Y neuroblastoma cells were treated with ATX (1, 5, 10, 20 and 50 μM) for 7 days under differentiation culture conditions. Changes in the expression levels of protein markers for mitochondrial biogenesis, fusion and fission as well as of antioxidant proteins were analysed by Western blot. High-dose ATX (50 μM) reduced while low-dose ATX (10 μM) increased mitochondrial biogenesis as evidenced by parallel changes in SDHA, COX-I, PGC1α and TFAM expression. High-dose ATX also reduced mitochondrial fusion as evidenced by OPA1 and MFN2 downregulation, and mitochondrial fission as indicated by DRP1 and Fis1 downregulation. In contrast, ATX did not alter expression of the antioxidant enzymes SOD1 and catalase, the phase II transcription factor Nfr2, or the Nfr2-regulated antioxidant enzyme NQO1. Clinical responses and side effects of ATX may be mediated by dose-dependent modulation of mitochondrial biogenesis and dynamics as well as NET inhibition.

The Effect of Meditation-Based Mind-Body Interventions on Symptoms and Executive Function in People With ADHD: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

This study aims to perform a systematic review and meta-analysis of the effect of MBIs (Mindfulness, Tai Chi, Yoga, and Qigong) on symptoms and executive function (EF) in ADHD.

METHOD

PubMed, Web of Science, the Cochrane Library, PsycINFO, CINAHL, Embase, and CNKI databases were searched to collect randomized controlled trials (RCTs) on the effects of MBIs on symptoms and EF in ADHD. Data extraction and methodological quality evaluation were conducted by two researchers, and a meta-analysis was conducted by Stata SE.

RESULTS

The pooled meta-analyses of MBIs revealed a positive and small effect on inattention (g = -0.26), hyperactivity/impulsivity (g = -0.19), and EF (g = -0.35).

CONCLUSION

Results suggest that MBIs have a significant improvement relative to the control condition. Although some results show that symptoms are affected by age, interventions, and total time of moderators, while EF is not affected by age and measurement, it needs to be supported by more research evidence. (J. of Att. Dis. XXXX; XX(X) XX-XX).

The translational genetics of ADHD and related phenotypes in model organisms

Attention-deficit/hyperactivity disorder (ADHD) is a highly prevalent neurodevelopmental disorder resulting from the interaction between genetic and environmental risk factors. It is well known that ADHD co-occurs frequently with other psychiatric disorders due, in part, to shared genetics factors. Although many studies have contributed to delineate the genetic landscape of psychiatric disorders, their specific molecular underpinnings are still not fully understood. The use of animal models can help us to understand the role of specific genes and environmental stimuli-induced epigenetic modifications in the pathogenesis of ADHD and its comorbidities. The aim of this review is to provide an overview on the functional work performed in rodents, zebrafish and fruit fly and highlight the generated insights into the biology of ADHD, with a special focus on genetics and epigenetics. We also describe the behavioral tests that are available to study ADHD-relevant phenotypes and comorbid traits in these models. Furthermore, we have searched for new models to study ADHD and its comorbidities, which can be useful to test potential pharmacological treatments.

A Potential Role for Neuroinflammation in ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurobehavioural disorder in children and adolescents. Although increases in oxidative stress and disturbances of neurotransmitter system such as the dopaminergic and abnormalities in several brain regions have been demonstrated, the pathophysiology of ADHD is not fully understood. Nevertheless, ADHD involves several factors that have been associated with an increase in neuroinflammation. This chapter presents an overview of factors that may increase neuroinflammation and play a potential role in the development and pathophysiology of ADHD. The altered immune response, polymorphisms in inflammatory-related genes, ADHD comorbidity with autoimmune and inflammatory disorders and prenatal exposure to inflammation are associated with alterations in offspring brain development and are a risk factor; genetic and environmental risk factors that may increase the risk for ADHD and medications can increase neuroinflammation. Evidence of an association between these factors has been an invaluable tool for research on inflammation in ADHD. Therefore, evidence studies have made it possible to generate alternative therapeutic interventions using natural products as anti-inflammatories that could have great potential against neuroinflammation in ADHD.

A Case Report on a Young Male Taking Methylphenidate With Fasciculations and Dysphagia: Correlation or Causation?

Concurrent fasciculations and oropharyngeal dysphagia (OD) can be presenting signs of motor neuron disease (MND); however, there are other causes for OD (neoplasms, surgery, and gastroesophageal diseases, among others). Fasciculations (anxiety, benign, or iatrogenic) are an uncommon side effect (<1%) of methylphenidate. A 30-year-old male noticed fasciculations in both gastrocnemii, reporting gradual cranial progression, culminating in diffuse fasciculations with facial involvement. One month later, he reported OD for solids and occasional cough for liquids. He denied weakness, fatigue, or weight loss. He has no relevant personal history, apart from attention deficit hyperactivity disorder diagnosed a year before and since then medicated with methylphenidate 40 mg id. He had no abnormal findings on neurological examination. Electromyography (EMG) and sinus CT were normal. Upper gastrointestinal (GI) endoscopy (EGD) showed reflux esophagitis grade C, which could explain OD, and he started esomeprazole 40 mg id. As there were no findings on EMG, an iatrogenic etiology for fasciculations was considered. He suspended methylphenidate for a month and, two months later, reported a substantial improvement in fasciculations and resolution of the OD with the introduction of esomeprazole. Two simultaneous symptoms do not mean they are related. In this specific case, OD was the first symptom of gastroesophageal reflux disease (GERD), and fasciculations happened as a side effect of methylphenidate. This must be taken into consideration, as it can represent a confounding factor making the differential diagnosis more difficult. To the best of our knowledge, there are no published articles similar to this case report.

Treatment of ADHD: Drugs, psychological therapies, devices, complementary and alternative methods as well as the trends in clinical trials

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders having a high influence on social interactions. The number of approved treatments and clinical trials for ADHD have increased markedly during the recent decade. This analytical review provides a quantitative overview of the existing pharmacological and non-pharmacological methods of ADHD treatments investigated in clinical trials during 1999-2021. A total of 695 interventional trials were manually assessed from clinicaltrial.gov with the search term « ADHD», and trial data has been used for analysis. A clear majority of the studies investigated non-pharmacological therapies (∼80%), including many behavioral options, such as social skills training, sleep and physical activity interventions, meditation and hypnotherapy. Devices, complementary and other alternative methods of ADHD treatment are also gaining attention. The pharmacological group accounts for ∼20% of all the studies. The most common drug classes include central nervous system stimulants (e.g., methylphenidate hydrochloride, lisdexamfetamine dimesylate, amphetamine sulfate, mixed amphetamine salts, a combination of dexmethylphenidate hydrochloride and serdexmethylphenidate chloride), selective noradrenaline reuptake inhibitors (atomoxetine, viloxazine), and alpha2 adrenergic receptor agonists (guanfacine hydrochloride, clonidine hydrochloride). Several studies investigated antidepressants (e.g., bupropion hydrochloride, vortioxetine), and atypical antipsychotics (e.g., quetiapine, aripiprazole) but these are yet not approved by the FDA for ADHD treatment. We discuss the quantitative trends in clinical trials and provide an overview of the new drug agents and non-pharmacological therapies, drug targets, and novel treatment options.

Reduced basal ganglia tissue-iron concentration in school-age children with attention-deficit/hyperactivity disorder is localized to limbic circuitry

Dopamine-related abnormalities in the basal ganglia have been implicated in attention-deficit/hyperactivity disorder (ADHD). Iron plays a critical role in supporting dopaminergic function, and reduced brain iron and serum ferritin levels have been linked to ADHD symptom severity in children. Furthermore, the basal ganglia is a central brain region implicated in ADHD psychopathology and involved in motor and reward functions as well as emotional responding. The present study repurposed diffusion tensor imaging (DTI) to examine effects of an ADHD diagnosis and sex on iron deposition within the basal ganglia in children ages 8-12 years. We further explored associations between brain iron levels and ADHD symptom severity and affective symptoms. We observed reduced iron levels in children with ADHD in the bilateral limbic region of the striatum, as well as reduced levels of iron-deposition in males in the sensorimotor striatal subregion, regardless of diagnosis. Across the whole sample, iron-deposition increased with age in all regions. Brain-behavior analyses revealed that, across diagnostic groups, lower tissue-iron levels in bilateral limbic striatum correlated with greater ADHD symptom severity, whereas lower tissue-iron levels in the left limbic striatum only correlated with anxious, depressive and affective symptom severity. This study sheds light on the neurobiological underpinnings of ADHD, specifically highlighting the localization of tissue-iron deficiency in limbic regions, and providing support for repurposing DTI for brain iron analyses. Our findings highlight the need for further investigation of iron as a biomarker in the diagnosis and treatment of ADHD and sex differences.

Evidence towards a continuum of impairment across neurodevelopmental disorders from basic ocular-motor tasks

Findings of genetic overlap between Schizophrenia, Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) contributed to a renewed conceptualization of these disorders as laying on a continuum based on aetiological, pathophysiological and neurodevelopmental features. Given that cognitive impairments are core to their pathophysiology, we compared patients with schizophrenia, ADHD, ASD, and controls on ocular-motor and manual-motor tasks, challenging crucial cognitive processes. Group comparisons revealed inhibition deficits common to all disorders, increased intra-subject variability in schizophrenia and, to a lesser extent, ADHD as well as slowed processing in schizophrenia. Patterns of deviancies from controls exhibited strong correlations, along with differences that posited schizophrenia as the most impaired group, followed by ASD and ADHD. While vector correlations point towards a common neurodevelopmental continuum of impairment, vector levels suggest differences in the severity of such impairment. These findings argue towards a dimensional approach to Neurodevelopmental Disorders’ pathophysiological mechanisms.

Striatal dopamine dissociates methylphenidate effects on value-based versus surprise-based reversal learning

Psychostimulants such as methylphenidate are widely used for their cognitive enhancing effects, but there is large variability in the direction and extent of these effects. We tested the hypothesis that methylphenidate enhances or impairs reward/punishment-based reversal learning depending on baseline striatal dopamine levels and corticostriatal gating of reward/punishment-related representations in stimulus-specific sensory cortex. Young healthy adults (N = 100) were scanned with functional magnetic resonance imaging during a reward/punishment reversal learning task, after intake of methylphenidate or the selective D_2/3-receptor antagonist sulpiride. Striatal dopamine synthesis capacity was indexed with [¹⁸F]DOPA positron emission tomography. Methylphenidate improved and sulpiride decreased overall accuracy and response speed. Both drugs boosted reward versus punishment learning signals to a greater degree in participants with higher dopamine synthesis capacity. By contrast, striatal and stimulus-specific sensory surprise signals were boosted in participants with lower dopamine synthesis. These results unravel the mechanisms by which methylphenidate gates both attention and reward learning.

The mechanisms underpinning the variability in methylphenidate’s effects on cognition remain unclear. Here, the authors show that such effects reflect changes in striatal dopamine-related output gating of task-relevant cortical signals, and that these changes depend on baseline dopamine synthesis capacity.

Curcumin for attention-deficit-hyperactivity disorder: a systematic review and preliminary behavioral investigation

Curcumin has protective actions in neuropsychiatric disorders, acting as a neuroprotective agent. As a first approach, the study aimed at a systematic review of the potential effects of curcumin on cognitive performance for attention-deficit-hyperactivity disorder (ADHD). This research was carried out in the databases of PubMed, Embase, SciELO, the Cochrane Central Register of Controlled Trials (CENTRAL), the Web of Science, and the Grey literature. Upon discovering the scarcity of relevant studies, and knowing that curcumin might have an ADHD hyperactive and anxious behavior, the study proposed to evaluate the effects of curcumin in an ADHD phenotype of spontaneously hypertensive Wistar rats (SHR). No studies were found that related to curcumin and ADHD. Fifteen SHRs were then divided into separate groups that received water (1 mg/kg/day), curcumin (50 mg/kg/day), or methylphenidate (1 mg/kg/day) for 42 days. Behavioral tests to assess activity (Open Field Test), anxiety and impulsivity (Elevated Plus-Maze, and Social Interaction), and memory (Y-Maze, and the Object Recognition Test) were all performed. The animals that were treated with curcumin showed less anxious and hyperactive behavior, as seen in the Open Field Test and the Social Interaction Test. Anxious behavior was measured by the EPM and was not modulated by any treatment. The results of the Y-Maze Test demonstrated that curcumin improved spatial memory. In the Object Recognition Test, neither the short nor the long-term memory was improved. The treatments that were used in this study beneficially modulated the anxious and hyperactive behavior of the SHR.

Cation-π Interactions between a Noble Metal and a Polyfunctional Aromatic Ligand: Ag+ (benzylamine)

The structure of an isolated Ag⁺ (benzylamine) complex is investigated by infrared multiple photon dissociation (IRMPD) spectroscopy complemented with quantum chemical calculations of candidate geometries and their vibrational spectra, aiming to ascertain the role of competing cation-N and cation-π interactions potentially offered by the polyfunctional ligand. The IRMPD spectrum has been recorded in the 800-1800 cm^-1 fingerprint range using the IR free electron laser beamline coupled with an FT-ICR mass spectrometer at the Centre Laser Infrarouge d'Orsay (CLIO). The resulting IRMPD pattern points toward a chelate coordination (N-Ag⁺ -π) involving both the amino nitrogen atom and the aromatic π-system of the phenyl ring. The gas-phase reactivity of Ag⁺ (benzylamine) with a neutral molecular ligand (L) possessing either an amino/aza functionality or an aryl group confirms N- and π-binding affinity and suggests an augmented silver coordination in the product adduct ion Ag + ( benzylamine ) ( L ) .

Tetrahydrobiopterin and Its Multiple Roles in Neuropsychological Disorders

Tetrahydrobiopterin (BH4) is a multifunctional co-factor of various enzymes and a substantial amount of studies have shown BH4 as a key regulator in the synthesis of neurotransmitters such as serotonin, nor-epinephrine as well as dopamine. The imbalance of BH4 may affect neurotransmitter production which can lead to many abnormalities in CNS. This article reviews the role of BH4 in neurodegenerative and neurodevelopmental disorders. We focus on the therapeutic potential of BH4 in various brain diseases that involves neurotransmitters and attempt to address how the modulation of BH4 may provide a novel strategy in various neuropsychological conditions.

The Development of the Mesoprefrontal Dopaminergic System in Health and Disease

Midbrain dopaminergic neurons located in the substantia nigra and the ventral tegmental area are the main source of dopamine in the brain. They send out projections to a variety of forebrain structures, including dorsal striatum, nucleus accumbens, and prefrontal cortex (PFC), establishing the nigrostriatal, mesolimbic, and mesoprefrontal pathways, respectively. The dopaminergic input to the PFC is essential for the performance of higher cognitive functions such as working memory, attention, planning, and decision making. The gradual maturation of these cognitive skills during postnatal development correlates with the maturation of PFC local circuits, which undergo a lengthy functional remodeling process during the neonatal and adolescence stage. During this period, the mesoprefrontal dopaminergic innervation also matures: the fibers are rather sparse at prenatal stages and slowly increase in density during postnatal development to finally reach a stable pattern in early adulthood. Despite the prominent role of dopamine in the regulation of PFC function, relatively little is known about how the dopaminergic innervation is established in the PFC, whether and how it influences the maturation of local circuits and how exactly it facilitates cognitive functions in the PFC. In this review, we provide an overview of the development of the mesoprefrontal dopaminergic system in rodents and primates and discuss the role of altered dopaminergic signaling in neuropsychiatric and neurodevelopmental disorders.

Gut microbiota and probiotic therapy in ADHD: A review of current knowledge

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by inattention, impulsivity and hyperactivity. The etiology of the disorder is multi-factorial, with a main focus on genetic factors. However, emerging research shows the involvement of changes and imbalances in the intestinal microbiota. Evidence for the influence of gut microbiota on brain development and neurogenesis is clear. We present a review of emerging research on the microbiota in the ADHD population. The aim of this study was to summarize the current state of knowledge on ADHD, to identify gaps in knowledge, as well as to indicate the directions of new research. Thanks to the researchers that would be possible to better understand the complexity of ADHD etiology, especially the role of the intestinal microbiota in the pathogenesis of the disorder. Pubmed, Scopus and Google Scholar databases were used while writing the review. Numerous studies show that probiotic supplementation can have a positive effect on the course of neurodevelopmental disorders, including ADHD. Unfortunately, clinical studies that were identified are mostly inconclusive, and more high-quality research is needed to produce robust evidence for therapy based on interventions targeting microbiota.

Efficacy and safety of methylphenidate on attention deficit hyperactivity disorder in children with Down syndrome

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common co-morbidity that affects up to 44% of children with Down syndrome (DS). There is a need for reliable, good quality research on the use of methylphenidate within this population. The objective of this study is to report our experience regarding the management of ADHD in these children using methylphenidate.

METHODS

This study is a retrospective observation of 21 children with DS, followed at Jérôme Lejeune Institute between 2000 and 2018. The diagnosis of ADHD was made using the Diagnostic and Statistical Manual of Mental Disorders criteria. Efficacy was measured as response or non-response on two main symptoms: attention/concentration and hyperactivity/impulsivity. Safety was evaluated by the presence or absence of side effects.

RESULTS

Sixteen out of the 21 children (76%) showed improvement with methylphenidate. The average age of treatment onset in responding children was 8 years and 10 months versus 6 years and 3 months in non-responders (P = 0.05). Average dose/weight was significantly different in responders and non-responders (0.82 vs. 0.54 mg/kg/day, respectively; P = 0.03). Twelve children out of 21 (57%) experienced side effects; only three experienced side effects severe enough to require treatment interruption. Most common side effects were loss of appetite and difficulties in falling asleep.

CONCLUSION

Methylphenidate was effective and safe in treating ADHD in 76% of cases in children with DS, with few serious side effects to report. Early diagnosis of ADHD is important to improve the quality of life, learning, inclusion and socialisation of children with DS.

Resting Theta/Beta Ratios Mediate the Relationship Between Motor Competence and Inhibition in Children With Attention Deficit/Hyperactivity Disorder

Despite that previous studies have supported relationships between motor ability and inhibitory function, and between resting brain theta/beta power ratios (TBR) and inhibition in children with attention deficit/hyperactivity disorder (ADHD), little research has examined the mechanism within these relationships. The purpose of this study was to investigate whether TBR would mediate the relationship between motor ability and inhibitory function. A total of 71 children with ADHD were recorded resting electroencephalographic (EEG) data during eyes-open. Motor abilities were evaluated by Movement Assessment Battery for Children-2 (MABC-2) and inhibitory ability were assessed by a modified Eriksen’s flanker task. The results of mediation analyses revealed that TBR could completely mediate the relationship between motor competence and response speed (indirect effect = −0.0004, 95% CI [−0.0010, −0.0001]) and accuracy (indirect effect = 0.0003, 95% CI [0.0000, 0.0010]) in the incongruent condition of the flanker task. This study suggests that TBR may be one of the mechanisms between motor ability and inhibition function in children with ADHD.

Adult ADHD: Influence of Physical Activation, Stimulation, and Reward on Cognitive Performance and Symptoms

Objective: Models of ADHD consider the influence of situational factors on cognitive performance and symptoms. Method: The influence of acute physical exercise, stimulation through continuous fine motor movement, and performance-related reward on performance and ADHD symptoms was assessed. Thirty-six adults with ADHD and 36 healthy controls performed executive function tasks (EF-tasks) of inhibition, selective attention, and working memory with material close to daily life. Experimental manipulations aimed at increasing cognitive performance. Results: No significant effects were found, but there were indicators for ADHD-specific impacts: Reward resulted in higher reported hyperactivity. Acute physical exercise slightly tended to improve attention performance and subjective inattention. Conclusion: The manipulations may affect performance and especially symptoms in different ways. Potential symptom interactions and identification of factors that determine whether symptoms may be functional or detrimental for task performance could be future research interests.

Current Evidence on the Role of the Gut Microbiome in ADHD Pathophysiology and Therapeutic Implications

Studies suggest that the bidirectional relationship existent between the gut microbiome (GM) and the central nervous system (CNS), or so-called the microbiome–gut–brain axis (MGBA), is involved in diverse neuropsychiatric diseases in children and adults. In pediatric age, most studies have focused on patients with autism. However, evidence of the role played by the MGBA in attention deficit/hyperactivity disorder (ADHD), the most common neurodevelopmental disorder in childhood, is still scanty and heterogeneous. This review aims to provide the current evidence on the functioning of the MGBA in pediatric patients with ADHD and the specific role of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in this interaction, as well as the potential of the GM as a therapeutic target for ADHD. We will explore: (1) the diverse communication pathways between the GM and the CNS; (2) changes in the GM composition in children and adolescents with ADHD and association with ADHD pathophysiology; (3) influence of the GM on the ω-3 PUFA imbalance characteristically found in ADHD; (4) interaction between the GM and circadian rhythm regulation, as sleep disorders are frequently comorbid with ADHD; (5) finally, we will evaluate the most recent studies on the use of probiotics in pediatric patients with ADHD.

The Co-occurrence of Pediatric Obesity and ADHD: an Understanding of Shared Pathophysiology and Implications for Collaborative Management

PURPOSE OF REVIEW

To describe what is known about the association between obesity and attention-deficit hyperactivity disorder (ADHD) in children along with the co-occurring conditions of sleep dysfunction, loss of control/binge eating disorder (LOC-ED/BED), and anxiety.

RECENT FINDINGS

Obesity and ADHD share common brain pathways (hypothalamic, executive, and reward centers) with pathophysiology in these areas manifesting in partial or complete expression of these diseases. Sleep dysfunction, LOC-ED/BED, and anxiety share similar pathways and are associated with this disease dyad. The association of obesity and ADHD with sleep dysfunction, LOC-ED/BED, and anxiety is discussed. An algorithm outlining decision pathways for patients with obesity and with and without ADHD is presented. Future research exploring the complex pathophysiology of both obesity and ADHD as well as co-occurring conditions is needed to develop clinical guidelines and ultimately assist in providing the best evidence-based care.

Methylphenidate boosts choices of mental labor over leisure depending on striatal dopamine synthesis capacity

The cognitive enhancing effects of methylphenidate are well established, but the mechanisms remain unclear. We recently demonstrated that methylphenidate boosts cognitive motivation by enhancing the weight on the benefits of a cognitive task in a manner that depended on striatal dopamine. Here, we considered the complementary hypothesis that methylphenidate might also act by changing the weight on the opportunity cost of a cognitive task, that is, the cost of foregoing alternative opportunity. To this end, 50 healthy participants (25 women) completed a novel cognitive effort-discounting task that required choices between task and leisure. They were tested on methylphenidate, placebo, as well as the selective D2-receptor agent sulpiride, the latter to strengthen inference about dopamine receptor selectivity of methylphenidate's effects. Furthermore, they also underwent an [18F]DOPA PET scan to quantify striatal dopamine synthesis capacity. Methylphenidate boosted choices of cognitive effort over leisure across the group, and this effect was greatest in participants with more striatal dopamine synthesis capacity. The effects of sulpiride did not reach significance. This study strengthens the motivational account of methylphenidate's effects on cognition, and suggests that methylphenidate reduces the cost of mental labor by increasing striatal dopamine.

A systematic review of transcranial direct current stimulation effects in attention-deficit/hyperactivity disorder

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) stands out as the most prevalent neurodevelopmental disorder of childhood, with global prevalence ranging from 3.4% to 7•2%. Its cognitive symptoms result from the combination of complex etiological processes encompassing genetic and environmental components. Available therapeutic approaches are associated with significant challenges such as modest efficacy or side effects. Transcranial direct current stimulation (tDCS) is a promising tool for enhancing cognitive performance in neuropsychiatric disorders. Trials investigating its applicability in ADHD have showed propitious, however, still preliminary findings.

METHODS

We performed a systemic review by searching on Medline, Cochrane Library, Web of Science, ScienceDirect and Embase using the descriptors: "attention-deficit/hyperactivity disorder" or "ADHD"; and "transcranial direct current stimulation" or "tDCS"; following PRISMA guidelines.

RESULTS

A total of 383 articles were identified. After removing duplicates, 45 studies were assessed for eligibility, and after careful review, 11 manuscripts applying tDCS in ADHD were included. Significant improvements in attention, inhibitory control and working memory were reported, in addition to increased brain connectivity following use of active tDCS.

LIMITATIONS

The main limitation was the small number of trials investigating use of tDCS in ADHD. Study methods and outcome measures were quite variable, and generally did not include long-term follow-up.

CONCLUSIONS

Although the extent literature indicates promising findings, the available data remains highly preliminary. Further trials evaluating the efficacy of tDCS for ADHD, with longer follow-up, are necessary. These studies will be needed to determine the optimal protocol for clinical efficacy.

Role of Oxidative Stress and Neuroinflammation in Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder of childhood. Although abnormalities in several brain regions and disturbances of the catecholaminergic pathway have been demonstrated, the pathophysiology of ADHD is not completely understood, but as a multifactorial disorder, has been associated with an increase in oxidative stress and neuroinflammation. This review presents an overview of factors that increase oxidative stress and neuroinflammation. The imbalance between oxidants and antioxidants and also the treatment with medications are two factors that can increase oxidative damage, whereas the comorbidity between ADHD and inflammatory disorders, altered immune response, genetic and environmental associations, and polymorphisms in inflammatory-related genes can increase neuroinflammation. Evidence of an association with these factors has become valuable for research on ADHD. Such evidence opens up new intervention routes for the use of natural products as antioxidants that could have potential as a treatment against oxidative stress and neuroinflammation in ADHD.

Methylphenidate challenge test in adults with attention deficit/hyperactivity disorder (ADHD): Clinical effects and their predictors

OBJECTIVE

Adult and children attention deficit/hyperactivity disorder (ADHD) share similar symptoms and responses to drugs such as methylphenidate (MPH). Yet, in Europe, these drugs remain unlicensed for adults. We aimed to assess the effects of an acute MPH challenge on the four dimensions concentration, impulsivity, tension, and general well-being in ADHD adults, and identify predictors of improvement.

METHODS

Therapeutic Drug Monitoring was performed to measure MPH plasma levels. A Visual Analogue Scale was administered to patients before and after the acute MPH challenge to measure self-reported changes in the four dimensions.

RESULTS

After the acute MPH challenge, our 71 patients showed significant improvement in concentration and tension. The MPH challenge dose correlated with lower patients' age, greater side effects, increased concentration (p = .008) and decreased tension (p = .001). At multiple linear regression MPH plasma levels and absence of postdose side effects predicted concentration improvement, MPH plasma levels predicted tension improvement. MPH plasma levels were significantly higher in patients who reported an improvement in concentration, tension, and impulsivity compared to nonimprovers (p's from .001 to .004).

CONCLUSIONS

These findings point to the efficacy of MPH challenge in improving concentration and tension in adult ADHD, thus emphasizing the need for a broader treatment access for these patients.

Neurobehavioral changes arising from early life dopamine signaling perturbations

Dopamine (DA) signaling is critical to the modulation of multiple brain functions including locomotion, reinforcement, attention and cognition. The literature provides strong evidence that altered DA availability and actions can impact normal neurodevelopment, with both early and enduring consequences on anatomy, physiology and behavior. An appreciation for the developmental contributions of DA signaling to brain development is needed to guide efforts to preclude and remedy neurobehavioral disorders, such as attention-deficit/hyperactivity disorder, addiction, bipolar disorder, schizophrenia and autism spectrum disorder, each of which exhibits links to DA via genetic, cellular and/or pharmacological findings. In this review, we highlight research pursued in preclinical models that use genetic and pharmacological approaches to manipulate DA signaling at sensitive developmental stages, leading to changes at molecular, circuit and/or behavioral levels. We discuss how these alterations can be aligned with traits displayed by neuropsychiatric diseases. Lastly, we review human studies that evaluate contributions of developmental perturbations of DA systems to increased risk for neuropsychiatric disorders.

Attention-Deficit/Hyperactivity Disorder, Its Pharmacotherapy, and Adrenal Gland Dysfunction: A Nationwide Population-Based Study in Taiwan

This study aims to examine the co-occurrence rate of attention deficit hyperactivity disorder (ADHD) and adrenal gland disorders, as well as whether pharmacotherapy may affect ADHD patients’ risk of developing adrenal gland disorder. One group of patients newly diagnosed with ADHD (n = 75,247) and one group of age- and gender-matching controls (n = 75,247) were chosen from Taiwan′s National Health Insurance database during the period of January 1999 to December 2011. Both patients and controls were monitored through December 31, 2011, in order to identify the occurrence of adrenal gland disorders (ICD-9-CM code 255.X). We also explored the potential effect of methylphenidate (MPH) and atomoxetine (ATX) treatments on the risk of developing adrenal gland disorders. We found that ADHD patients showed a significantly increased probability of developing an adrenal gland disorder compared to the control group (0.2% of ADHD vs. 0.1% of controls). However, neither MPH nor ATX treatment significantly influenced the patients’ risk of developing adrenal gland dysfunction. We propose that patients with ADHD had greater comorbid rates with adrenal gland dysfunction than the control subjects. Nevertheless, undergoing treatment with MPH or ATX did not significantly influence the risk of developing adrenal gland dysfunction among ADHD patients.

The Novelty of Bupropion As a Dopaminergic Antidepressant for the Treatment of Adult Attention Deficit Hyperactive Disorder

Attention deficit hyperactive disorder (ADHD), a hyperactivity disorder prevalent among children may continue as an adulthood attention deficit. To date, treating an individual with an adult ADHD may be an arduous task as it involves numerous challenges, which include a need for high index of suspicion to diagnose this medical condition. Many psychiatric disorders masquerade as ADHD and delay the necessary assessment and proper treatment for this debilitating medical disorder. Adult ADHD is often misdiagnosed (or under diagnosed) due to the fact that this medical condition is being masked by the patients' high level of intellectual achievement. As the ADHD in adult persists, it may end-up with impairment in the personal-social-occupational function in which the management becomes a great challenge. The treatment of ADHD can be optimized by using various drugs targets agents like norepinephrine-dopamine reuptake inhibitor (NDRI), with or without psycho stimulants like methylphenidate, which is marketed as Ritalin. Bupropion, an NDRI has a novel effect on ADHD as the molecule exerts its effects by modulating the reward-pleasure mesolimbic dopaminergic system and at the same time regulates the elevating mood dimension of the noradrenergic neurotransmission. The role of Bupropion in the neural and psychopharmacological perspective treatment of ADHD was deliberated. The present review highlights the novel effects of Bupropion in ADHD treatment, together with the help of other successful bio-psycho-social measures. This may be of immense benefit to the psychiatrists for treating their patients.

Association between BDNF gene polymorphisms and attention deficit hyperactivity disorder in school-aged children in Wuhan, China

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is vital for neuronal survival and growth, regulation of synaptic plasticity, and cognitive function. Previous studies examined the role of BDNF in susceptibility to attention deficit hyperactivity disorder (ADHD). The current study examined the association between BDNF gene polymorphisms and ADHD in Chinese children.

METHODS

Participants were 195 medication-naive ADHD children and 263 unaffected healthy controls. ADHD symptoms were diagnosed using the Vanderbilt ADHD Diagnostic Parental Rating Scale according to the Diagnostic and Statistical Manual of Mental Disorders-5. Five BDNF single nucleotide polymorphisms were detected using improved multiplex ligation detection reaction. Alleles and genotype frequency were examined using Chi-square tests. Correlations were examined using multivariate logistic regression analysis in the ADHD and control groups.

RESULTS

The results revealed that rs12291186 with one or both mutated allele(s) was significantly associated with reduced likelihood of ADHD (OR = 0.13, 95% CI: 0.02-0.77) and ADHD-Combined (OR = 0.10, 95% CI: 0.01-0.85). Children with genotype AA or CA in rs10835210 exhibited increased risk of ADHD (OR = 3.29, 95% CI: 1.03-10.55) and ADHD-Combined (OR = 4.45, 95% CI: 1.10-17.96) compared with genotype CC children. No significant associations were found between rs6265, rs7103411, rs7103873 polymorphisms and ADHD.

LIMITATIONS

Participants were recruited from urban areas. We were unable to examine all potential confounding factors.

CONCLUSIONS

BDNF gene polymorphisms of rs12291186 and rs10835210 were related to the occurrence of ADHD. These findings provide new insight on mechanisms underlying BDNF gene in ADHD.

Antioxidants as a Potential Target against Inflammation and Oxidative Stress in Attention-Deficit/Hyperactivity Disorder

Psychostimulants and non-psychostimulants are the medications prescribed for the treatment of attention-deficit/hyperactivity disorder (ADHD). However, several adverse results have been linked with an increased risk of substance use and side effects. The pathophysiology of ADHD is not completely known, although it has been associated with an increase in inflammation and oxidative stress. This review presents an overview of findings following antioxidant treatment for ADHD and describes the potential amelioration of inflammation and oxidative stress using antioxidants that might have a future as multi-target adjuvant therapy in ADHD. The use of antioxidants against inflammation and oxidative conditions is an emerging field in the management of several neurodegenerative and neuropsychiatric disorders. Thus, antioxidants could be promising as an adjuvant ADHD therapy.

Enhanced Nitric Oxide (NO) and Decreased ADMA Synthesis in Pediatric ADHD and Selective Potentiation of NO Synthesis by Methylphenidate

Attention deficit hyperactivity disorder (ADHD) is a common pediatric psychiatric disorder, frequently treated with methylphenidate (MPH). Recently, MPH’s cardiovascular safety has been questioned by observational studies describing an increased cardiovascular risk in adults and blood pressure alterations in children. We considered members of the L-arginine (Arg)/nitric oxide (NO) pathway as possible early cardiovascular risk factors in pediatric ADHD children. They include the NO metabolites, nitrite and nitrate, the NO precursor Arg, and asymmetric dimethylarginine (ADMA), an endogenous NO synthase (NOS) inhibitor and a cardiovascular risk factor in adults. We conducted a prospective clinical trial with 42 ADHD children (aged 6–16 years) with (n = 19) and without (n = 23) MPH treatment. Age-matched children without ADHD (n = 43) served as controls. All plasma and urine metabolites were determined by gas chromatography-mass spectrometry. We observed higher plasma nitrite and lower plasma ADMA concentrations in the ADHD children. MPH-treated ADHD children had higher plasma nitrite concentrations than MPH-untreated ADHD children. As NOS activity is basally inhibited by ADMA, MPH treatment seems to have decreased the inhibitory potency of ADMA. Percentiles of systolic blood pressure were higher in MPH-treated ADHD children. The underlying mechanisms and their implications in the MPH therapy of pediatric ADHD with MPH remain to be elucidated in larger cohorts.

Physical exercise in attention deficit hyperactivity disorder - evidence and implications for the treatment of borderline personality disorder

A growing body of literature indicates a potential role for physical exercise in the treatment of attention deficit hyperactivity disorder (ADHD). Suggested effects include the reduction of ADHD core symptoms as well as improvements in executive functions. In the current review, we provide a short overview on the neurophysiological mechanisms assumed to underlie the beneficial effects of exercise. Further, we review the current evidence from experimental studies regarding both acute exercise and long-term interventions in ADHD. While the positive effects observed after acute aerobic exercise are promising, very few well-designed long-term intervention studies have been conducted yet. Moreover, although exercise effects have not yet been studied in borderline personality disorder (BPD), in the end of this paper we derive hypotheses why exercise could also be beneficial for this patient population.

Transcriptome-wide association study of attention deficit hyperactivity disorder identifies associated genes and phenotypes

Attention deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental psychiatric disorder. Genome-wide association studies (GWAS) have identified several loci associated with ADHD. However, understanding the biological relevance of these genetic loci has proven to be difficult. Here, we conduct an ADHD transcriptome-wide association study (TWAS) consisting of 19,099 cases and 34,194 controls and identify 9 transcriptome-wide significant hits, of which 6 genes were not implicated in the original GWAS. We demonstrate that two of the previous GWAS hits can be largely explained by expression regulation. Probabilistic causal fine-mapping of TWAS signals prioritizes KAT2B with a posterior probability of 0.467 in the dorsolateral prefrontal cortex and TMEM161B with a posterior probability of 0.838 in the amygdala. Furthermore, pathway enrichment identifies dopaminergic and norepinephrine pathways, which are highly relevant for ADHD. Overall, our findings highlight the power of TWAS to identify and prioritize putatively causal genes.

A recent GWAS reported 12 genetic loci for attention deficit/hyperactivity disorder (ADHD). Here, Liao et al. perform transcriptomic imputation using these data and 12 brain-relevant tissues from GTEx and CMC to identify 9 genes associated with ADHD by TWAS, 3 of which had not yet been reported for ADHD.

Atomoxetine produces oxidative stress and alters mitochondrial function in human neuron-like cells

Atomoxetine (ATX) is a non-stimulant drug used in the treatment of attention-deficit/hyperactivity disorder (ADHD) and is a selective norepinephrine reuptake inhibitor. It has been shown that ATX has additional effects beyond the inhibition of norepinephrine reuptake, affecting several signal transduction pathways and alters gene expression. Here, we study alterations in oxidative stress and mitochondrial function in human differentiated SH-SY5Y cells exposed over a range of concentrations of ATX. We found that the highest concentrations of ATX in neuron-like cells, caused cell death and an increase in cytosolic and mitochondrial reactive oxygen species, and alterations in mitochondrial mass, membrane potential and autophagy. Interestingly, the dose of 10 μM ATX increased mitochondrial mass and decreased autophagy, despite the induction of cytosolic and mitochondrial reactive oxygen species. Thus, ATX has a dual effect depending on the dose used, indicating that ATX produces additional active therapeutic effects on oxidative stress and on mitochondrial function beyond the inhibition of norepinephrine reuptake.

Novel approach to evaluate central autonomic regulation in attention deficit/hyperactivity disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD) is one of the most commonly diagnosed developmental disorders in childhood characterized by hyperactivity, impulsivity and inattention. ADHD manifests in the child's development by deficits in cognitive, executive and perceptor-motor functions, emotional regulation and social adaptation. Although the exact cause has not yet been known, the crucial role in the development of this disease plays the interaction of genetic, neurobiological and epigenetic factors. According to current knowledge, ADHD is defined as a biological dysfunction of central nervous system with genetically or organically defined deficits in noradrenergic and dopaminergic neurotransmission associated with structural abnormalities, especially in prefronto-striatal regions. In this context, a significant part of the difficulties could be due to a faulty control of fronto-striato-thalamo-cortical circuits important for attention, arousal and executive functions. Moreover, ADHD is associated with abnormal autonomic regulation. Specifically, reduced cardiac-linked parasympathetic activity associated with relative sympathetic dominance indexed by low heart rate variability can represent a noninvasive marker for prefrontal hypoactivity. However, the mechanisms underlying altered autonomic regulation in ADHD are still unknown. In this aspect, the evaluation of central autonomic regulation by noninvasive methods, namely pupillometry and eye-tracking, may provide novel information for better understanding of the neurobiological pathomechanisms leading to ADHD.